Question: Simplify the following expression: $t = \dfrac{z}{3} - \dfrac{z}{2}$
Solution: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $3$ and $2$ $\lcm(3, 2) = 6$ $ t = \dfrac{2}{2} \cdot \dfrac{z}{3} - \dfrac{3}{3} \cdot \dfrac{z}{2} $ $t = \dfrac{2z}{6} - \dfrac{3z}{6}$ $t = \dfrac{2z -3z}{6}$ $t = \dfrac{-z}{6}$